Cytochromes P450 monooxygenases from the CYP98 family catalyze the meta-hydroxylation step in the phenylpropanoid biosynthetic pathway. The ref8 Arabidopsis (Arabidopsis thaliana) mutant, with a point mutation in the CYP98A3 gene, was previously described to show developmental defects, changes in lignin composition, and lack of soluble sinapoyl esters. We isolated a T-DNA insertion mutant in CYP98A3 and show that this mutation leads to a more drastic inhibition of plant development and inhibition of cell growth. Similar to the ref8 mutant, the insertion mutant has reduced lignin content, with stem lignin essentially made of p-hydroxyphenyl units and trace amounts of guaiacyl and syringyl units. However, its roots display an ectopic lignification and a substantial proportion of guaiacyl and syringyl units, suggesting the occurrence of an alternative CYP98A3-independent meta-hydroxylation mechanism active mainly in the roots. Relative to the control, mutant plantlets produce very low amounts of sinapoyl esters, but accumulate flavonol glycosides. Reduced cell growth seems correlated with alterations in the abundance of cell wall polysaccharides, in particular decrease in crystalline cellulose, and profound modifications in gene expression and homeostasis reminiscent of a stress response. CYP98A3 thus constitutes a critical bottleneck in the phenylpropanoid pathway and in the synthesis of compounds controlling plant development. CYP98A3 cosuppressed lines show a gradation of developmental defects and changes in lignin content (40% reduction) and structure (prominent frequency of p-hydroxyphenyl units), but content in foliar sinapoyl esters is similar to the control. The purple coloration of their leaves is correlated to the accumulation of sinapoylated anthocyanins.

Cyclodextrins are cyclic oligosaccharides with the shape of a hollow truncated cone. Their exterior is hydrophilic and their cavity is hydrophobic, which gives cyclodextrins the ability to accommodate hydrophobic molecules/moieties in the cavity. This special molecular arrangement accounts for the variety of beneficial effects cyclodextrins have on proteins, which is widely used in pharmacological applications. We have studied the interaction between beta-cyclodextrin and four non-carbohydrate-binding model proteins: ubiquitin, chymotrypsin inhibitor 2 (CI2), S6 and insulin SerB9Asp by NMR spectroscopy at varying structural detail. We demonstrate that the interaction of beta-cyclodextrin and our model proteins takes place at specific sites on the protein surface, and that solvent accessibility of those sites is a necessary but not compelling condition for the occurrence of an interaction. If this behaviour can be generalized, it might explain the wide range of different effects of cyclodextrins on different proteins: aggregation suppression (if residues responsible for aggregation are highly solvent accessible), protection against degradation (if point of attack of a protease is sterically 'masked' by cyclodextrin), alteration of function (if residues involved in function are 'masked' by cyclodextrin). The exact effect of cyclodextrins on a given protein will always be related to the particular structure of this protein.

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Rice hulls are a relatively high‐volume, low‐cost by‐product commodity which contains the two basic components needed to produce silicon: silica and carbon. Impurity analyses have indicated that rice hulls from various sources are compositionally similar and that they have low concentrations (10–20 ppmw) of aluminum and iron, the major impurities in conventional raw materials used to prepare metallurgical silicon. The levels of the major impurities (Ca, K, Mg, and Mn) in rice hulls can be reduced by about a factor of 100 to around 20 ppmw by hot hydrochloric acid leaching. The doping impurities boron and phosphorus, important in silicon intended for solar cells, were less affected by acid leaching. Their concentrations were found to be 1 and 40 ppmw, respectively, in leached hulls. Coking of unpurified rice hulls produced a material with a C:SiO2 ratio of about 4:1. An increase in concentrations of some impurities was noted since coking results in about a 67% loss in sample weight. The coked hulls were extruded with sucrose as a binder to produce 5 mm diam pellets with an average bulk density of about 800 g/l. The pellets gave favorable changes in bulk density and compression strength with increasing percentage sucrose. The abrasiveness of silica caused die wear in the extruder, resulting in roughly a doubling of the original concentration of iron in the coked hulls. Coked rice hull pellets showed excellent reactivity for producing silicon. Laboratory tests employing the reaction of silicon monoxide with carbon in the pellet showed very high reactivities for both purified and unpurified materials. A test in a small arc furnace of unpurified material showed energy consumption per unit weight of silicon to be about 15%–30% lower than normal. Unpurified rice hulls were used for these tests. Although the silicon produced in the arc furnace test was contaminated, estimates of silicon purity attainable from coked hulls, unpurified and purified, indicate their potential as raw materials for the production of MG‐Si and solar‐grade silicon.

The emission of volatile organic compounds (VOC) from nine toner powders and eleven types of processed paper from photocopying machines (6), laser (3) and matrix printers (21, and one carbonless copy fm has been measured. A total of 61 VOC from toner powders were identified by heating (185 °C) the powder for three minutes for thermal desorption and by gas chromatography followed by the use of low and high resolution EI and CI mass spectrometry. VOC from processed paper were analyzed by headspace sampling on Tenax TA from nylon bags. Thirty‐one VOC with a wide range of volatility and persistency were identified from processed paper. The total VOC emission from the various types of paper differed substantially. Using the field and laboratory emission cell (FLEC), the calculated initial emission rate of styrene was 5 μg m−2h−1 from a freshly processed paper The VOC emission from machines and the processed paper can be reduced by proper choice of o m e equipment. However, an evaluation should consider all potential pollutants.

This work investigates the isotropic etching properties of an inductively coupled plasma (ICP) etcher for masked and maskless etching steps in reference to fabrication of a silicon microlens mold. Using the described method a wide range of lens geometries and lens arrays with 100% fill factor can be achieved. The silicon etching is performed with a continuous SF6 based ICP. Analysis of the etching profile was done by SEM inspection and by optical interferometric measurements. For the masked etching step a consistent picture of the profile evolution is obtained, including a relation between the etching depth, the radius of curvature of the profile, the etching time and the size of the mask opening. For the maskless etching step, the optimal etch is purely isotropic. Within the tested process parameter range the maskless etching showed a non-isotropic behavior, which results in lens aberrations, crystal orientation dependence, poor uniformity and roughness. Generally a trade-off between the individual etching behaviors is found, but useful etching recipes can be found for a range of different lens geometries.

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